WASHINGTON
— A timely photo op with President Bush and a tribute at the Capitol Hilton next week signal how seriously official Washington is taking the next round of ethics investigations around embattled House leader Tom DeLay.

It's an investigation that the House majority leader says he welcomes, to clear his name. But it's also threatening to engulf other members of Congress, as opposition researchers for both parties plunge into member disclosure forms in search of lapses. The looming ethics war could write a new chapter in an long-running story of money, power, and boundary lines in Washington.

Congress has come a long way from the days when Sen. Daniel Webster penned an 1833 letter reminding banking interests that his "annual retainer" was due and important banking legislation was coming up in the US Senate. Today, he'd be swiftly expelled and prosecuted.

But even as standards have risen, so has the volume of dollars flowing through the capital. At the root of the DeLay investigation: How many degrees of separation are appropriate between lobbyist cash and politicians? The search for answers could tarnish both parties.

equivalent of mutually assured destruction," says Mike Franc, vice president for government relations at the Heritage Foundation. "There will be a retaliation of equal or greater force."

After months of deadlock - and a repeal of GOP-drafted ethics rule muscled through the House at the start of the new Congress - the House ethics panel is expected to organize this week. At the top of its agenda is the swirl of allegations around DeLay.

If confirmed, the charges that lobbyists paid for DeLay's travel to Russia, London, Scotland, and South Korea would be a violation of House rules. He also faces a deferred ethics complaint over alleged illegal corporate contributions to a group in Texas that he helped found.

The first signs of retaliation surfaced last week, as freshmen Reps. Patrick McHenry (R) of North Carolina and Lynn Westmoreland (R) of Georgia chastised minority whip Steny Hoyer (D) of Maryland for failing to file required 30-day travel disclosure forms over a number of years. Democrats call these procedural or technical corrections.

Last week, House Democratic leader Nancy Pelosi filed a late report for an aide whose trip to South Korea was financed by a group that had registered as a foreign agent, which appears to violate House rules. Current House rules do not forbid members from accepting privately financed travel. But lawmakers are required to "make inquiry about the source of the funds" for the trip.

According to public disclosure forms, DeLay took 14 trips paid for by private interests worth just over $94,000 since 2000, but 27 lawmakers took trips from private groups that were valued more. Since 2000, members of Congress have taken more than $16 million in privately financed trips, according to an analysis by PoliticalMoneyLine, an online public interest research group.

"A lot of folks don't understand the rules and regulations relative to travel," says James Albertine, president of Albertine Enterprises and a longtime lobbyist. "Most lobbyists want to be ethical, but we live in a very complex town. The ability to get time with members has become a very important part of the profession."

Last week, The Washington Post reported that expenses for a privately funded golfing trip to Scotland in 2000 were covered by a credit card in the name of Washington lobbyist Jack Abramoff, who is currently under investigation by a Senate committee and the Justice Department over some $80 million in fees for work on behalf of Indian gambling interests on Capitol Hill.

Public interest groups say such travel payments would violate House rules. "The rules are clear: A lobbyist can't advance funds for travel," says Larry Noble of the Center for Responsive Politics.

Even so, the lobbyist provision is a fig leaf, critics say. "The lobbyist can't pay for the trip, and a lobbying firm can't pay for the trip, but the client can," says Mr. Noble. That client is a nonprofit group, which may have ties to industry. "So, the lobbyist still gets the benefit of going along with the member."

But lobbyists and some members of Congress say there is ambiguity in how the rules are interpreted. Paul Miller, president of the American League of Lobbyists, says it's not unusual for lobbyists to help set up or arrange a trip. "I don't see that that's an issue. But the money has to come from a nonprofit. The lobbyist is acting as nothing more than a conduit for helping arrange that travel." As to whether a lobbyist can cover expenses for members of Congress with a credit card and be reimbursed by clients at a later date, he says: "That's to be discussed."

As the DeLay travel flap heated up, members are already wary about future privately sponsored travel. The conservative Heritage Foundation finds members reluctant to sign up for its annual summer policy wonker on social security.

"DeLay's ethics woes will have a chilling effect on congressional travel," says Rep. Harold Ford (D) of Tennessee, who ranks No. 2 in the number of trips paid for by private groups. Travel often helps members understand the issues, he says.

Meanwhile, House Democrats Rahm Emanuel of Illinois and Marty Meehan of Massachusetts are developing a proposal to require lobbyists to disclose ties with nonprofit groups and the way private groups pay for travel. The bill would also double the time members and staff will have to wait after leaving Congress before becoming lobbyists to former colleagues.

At issue in the next round of ethics wars - and the reforms that follow - is how to break the appearance that Washington runs on a pay-to-play basis. After taking back the House in 1995, Republicans increased lobbyist disclosure requirements as well as restrictions on gifts they could give to lawmakers. It's these disclosure requirements that are providing grist for the next rounds in an ethics war.

"Power, if it doesn't corrupt, makes people numb to appearances. It happens over and over again," says Brooks Jackson, whose 1988 book "Honest Graft" helped define the last ethics war.